Ambient

Ambient music is a musical genre that is generally identifiable as being broadly atmospheric and environmental in nature.
Ambient music evolved from early 20th century forms of semi-audible music, from the impressionism of Erik Satie, through "musique concrete" and the minimalism of Terry Riley and Philip Glass, and Brian Eno's deliberate sub-audible approach.
Later developments found the dreamy non-linear elements of ambient music applied to some forms of rhythmic music presented in chill-out rooms at raves and other dance events Read more on Last.fm.